The Aging Research Center Laboratory Animal Core will operate as a shared resource, to facilitate and coordinate animal model studies for all five projects in this proposal. This core will build upon existing colonies from two different project members (Granholm and Rohrer) to develop disease-free, carefully phenotyped colonies of conventional, aged and growth factor knockout mice, in order to provide a common animal stock and therefore to reduce variables that could compromise data analysis between projects. This continuity will permit a more complete evaluation and will facilitate the consolidation of data for an accurate model of aging of the dopaminergic system. Aim #1. The first specific aim if this Core is to provide specialized maintenance of knockout and control mice, both as young and aged individuals; to provide sufficient breeding pairs and animals of particular age groups to the individual projects; to provide genotyping services as part of the ongoing effort to develop and maintain these specialized colonies; and to coordinate the sharing of animal resources. Aim #2 The second specific aim is to provide regular comprehensive health evaluations for all animals in the Core facility. This will include regular serological tests to maintain a disease-free status of all animals, diagnostic gross and histopathological examinations for all experimental animals to provide baseline levels for all parameters tested, as well as final evaluations at the completion of the experiments. Aim #3. A third specific aim is to provide a centralized facility to examine dopamine levels and metabolites for animals from all projects. Aim #4. The fourth aim is to centralize and standardize treatment paradigms, which increases the reproducibility of experiments between different projects. Aim #5. And in a final and fifth specific aim, Core personnel will maintain the database, which will include monitoring and tracking of all project animals, and which will be accessible via Web-interphase by all project members. Core members will input genotypes and all animal health and final pathological evaluations at necropsy into the database, and project members will input all animal-specific behavioral, physiological, neurochemical, cell-biological and molecular data. Well-maintained and centralized data records will facilitate post hoc comparisons and cross-correlation-based data analysis between all the data generated in the individual projects.